As electronic components and devices get smaller with increasing operational speed, generated heat becomes a major obstacle of improving performance of electronic devices and systems. A heatsink is a common device used to remove heat from a heat-generating device to the ambient environment.
In many applications, heat generated from an electronic device can be ejected into the air by heatsinks. Development of heatsinks has been a major focus of thermal management in electronic systems. The performance of a heatsink can be represented by a total thermal resistance. A lower resistance value represents a higher cooling/heat transfer performance. Conductive resistance and convective resistance can affect the total thermal resistance of a heatsink. Conductive resistance represents the ability of a heatsink to diffuse heat from contact point with the heat source to convective surfaces. In general, conductive resistance can be minimized by having a short thermal conduction path with a large cross-section area with highly conductive material, e.g., aluminum or copper. Convective resistance represents the ability of a heatsink to eject heat into the ambient environment with a given air flow configuration. In general, heatsink designs maximize the number of convective surfaces.
Heat pipes can be used to reduce conductive resistance, since evaporated vapor carries heat from the evaporation zone and releases the heat by condensation over the condensation surface. For instance, a flat-plate heatpipe has been used to reduce the spreading resistance at the base of a heatsink. Also, fins, which are heatpipes arranged in an array configuration, thermally connected with a solid base, can minimize conductive resistance along the fins. A flat-plate heatpipe can be combined with other heatpipes to form a base and fins.